1. Field of the Invention
The present invention relates to a rotary electric machine mounted on, for example, an internal combustion engine of a vehicle.
2. Background Art
FIG. 18 is a sectional view showing the conventional rotary electric machine, for example, an AC generator for the vehicle. In the view, numeral 1 is a front bracket, numeral 2 is a rear bracket, and numeral 3 is a stator supported by the front bracket 1 and rear bracket 2, and which is structured by a stator core 4 and a stator winding 4 inserted in slots of the stator core 4.
Numeral 6 is a rotor whose both ends are fixed to a rotation shaft 7 supported by the front bracket 1 and the rear bracket 2, and is structured by the first rotor core 8, the second rotor core 9, a field coil 10 wound between both rotor cores 8 and 9, fans 11 and 12 provided on the back surface of both rotor cores 8 and 9, a pulley 13 provided outside of the front bracket 1 side of the rotation shaft 7, and a slip ring 14 which is provided inside of the rear bracket 2 side of the rotation shaft 7 and supplies the current to the field coil 10. The pulley 13 is engaged with one end of the rotation shaft 7, and connected to the rotation shaft 7 by a screw cut on one end of the rotation shaft 7 and a nut 20 screwed with that so that the pulley 13 can be rotated integrally with the rotation shaft 7.
Numeral 15 is a brush to supply the current to the slip ring 14, numeral 16 is a brush holder to hold the brush, numeral 17 is a rectifier to rectify the AC output of the stator winding 5, and numeral 18 is a regulator to adjust the current of the field coil 10 and to control the output voltage of the stator winding 5.
In the vehicle-use AC generator structured in this manner, the current is flowed from a battery, not shown, mounted on the vehicle to the field coil 10 through the brush 15 and slip ring 14, and when the rotor 6 is driven by the internal combustion engine through the pulley 13, the rotor 6 generates the rotating field, and this voltage is rectified by the rectifier 17 and supplied to the load, not shown.
However, in the conventional rotary electric machine, because the pulley 13 has the structure in which it is only engaged with the rotation shaft 7, there is a following problem. FIGS. 19A and 19B are typical view showing applied-ways of the running torque onto each position when the rotary electric machine is used as the generator. Because an engine is normally rotated clockwise, the clockwise drive force is transmitted to the pulley through a belt, and by the rotation shaft directly connected to the pulley, the generator is driven. As shown in FIG. 19A, at the time of the acceleration of the engine by the drive force of the belt, the pulley is rotated by the same clockwise torque as the engine, and the rotation shaft engaged with the pulley is also rotated by the clockwise torque in the same manner by being affected by the pulley. At this time, when the screw-thread cut on the rotation shaft is the right-handed screw, the nut to fix the pulley is rotated clockwise by the running torque of the rotation shaft and is in the fastening direction, therefore, there is no problem.
However, as shown in FIG. 19B, when the engine begins to be decelerated, the pulley has the force to resist the drive of the belt, that is, the counterclockwise torque reversed to the rotation of the engine. Because the pulley is only simply engaged with the rotation shaft, the pulley and rotation shaft are slidingly moved in the peripheral direction, and when the screw-thread cut on the rotation shaft is the right-handed screw, the nut to fix the pulley is rotated counterclockwise by the running torque and loosened, therefore, there is a problem that the rotation shaft is idly rotated.
Further, FIG. 20 is a typical view showing the applied way of the running torque onto each position when the rotary electric machine is used as a starter. The rotation shaft of the starter is rotated clockwise in the same direction as that of the engine, and the clockwise drive force is transmitted to the belt through the pulley, and the engine directly connected to the belt is driven. As shown in the drawing, at time of the start of the engine, the rotation shaft of the starter has the clockwise torque, and because the pulley is stopped initially, the pulley has the force to resist the rotation of the rotation shaft, that is, the counterclockwise torque reversed to the rotation of the rotation shaft. Because the pulley is only simply engaged with the rotation shaft, the pulley and rotation shaft are slidingly moved in the peripheral direction, and when the screw-thread cut on the rotation shaft is the right-handed screw, the nut to fix the pulley is rotated counterclockwise by the running torque and loosened, therefore, there is a problem that the rotation shaft is idly rotated. Particularly, in the vehicle in which an idling stop is adopted, because there, are many scenes to start the engine, the above problem becomes conspicuous.